8/21 – Brittany’s “Gloomy Conditions Ahead” Sunday Evening Forecast
A shortwave trough will move through the area over the next few days. Southerly surface winds will continue to enhance warm air and moisture advection, which will enhance instability in the environment. Weak upper level divergence will help enhance lifting, especially during the daytime hours the next few days. PW values are high around 2.2-2.4 inches, which is above the 90th percentile for SPC sounding climatology. Consequently, rainfall will be more efficient and produce higher rainfall rates inside stronger storms. Looking at the models, rainfall chances will be high daily for the next few days. PoPs are currently forecast in the 70s and 80s. General model consensus supports a wetter forecast and due to the abundant moisture moving through the area over the next few days, PoPs are a little higher than the NBM forecast. Locally heavy rainfall will be a concern daily over the next few days. We are still not seeing indications of widespread flooding, but isolated flooding will be possible, especially in low-lying or vulnerable areas if a strong storm develops. In addition to the rainfall risk, there will also be the potential for gusty subsevere winds and frequent lightning inside of stronger storms.
Weak upper level divergence, especially Wednesday and Thursday afternoons, will help to enhance lifting in the environment as well. PW values are forecast to remain high around 2.2-2.4 inches, which is above the 90th percentile for the SPC sounding climatology. Consequently, rainfall the develops will likely be more efficient and produce higher rainfall rates. Looking at models, rainfall is expected daily thanks to the shortwave and atmospheric conditions. Due to the abundant moisture, lifting, and weaker shear, locally heavy rainfall will be a concern daily mid week through the end of the week inside of stronger storms. It still does not appear to be a widespread flooding risk. But vulnerable areas will be at localized/isolated risk of flash flooding, given the efficiency of rainfall and warm rain processes. Additionally, subsevere gusty winds and frequent lightning will be a concern inside of stronger storms toward the end of the week.
